I don't understand how this car works.

@sirclicksalot,

Quote:

Do you agree a cart with a turbine on it driving the wheels could move directly upwind?

Well you could for example set the brakes and then spin up a flywheel and after releasing the brake move forward on the flywheel energy for a time.

So you could move directly upwind by stages if you wish to but I do not see steady stage movements.

2 Replies

@Cycloptichorn,

Cycloptichorn wrote:

Quote:
Now place that same windmill on a flat bed truck moving at the same velocity as the local wind and you would get zero energy from that windmill.

This is not true, because the windmill will still transform part of the wind which hits it's wings into rotational velocity... just like a tacking boat does.

Cycloptichorn

Actually, it is true. With no connection to the wheels of the truck, there is nothing to cause the blades of the windmill to turn.

0 Replies

@BillRM,

Bill,

Just gear down the wheels and you get steady-state movement upwind. You might not move very fast, but you will definitely move continually upwind.

This is almost trivial to describe. Have a windmill generate electrical power and have the electricity power the wheels. No flywheel needed.

2 Replies

@Cycloptichorn,

Quote:

This is not true, because the windmill will still transform part of the wind which hits it's wings into rotational velocity... just like a tacking boat does.

Not true.............as standing on the bed of that truck you could not tell by air movements if the truck was standing still with no wind or moving at wind speed instead.

Also by your thinking the windmill would be turning on a free floating balloon as the balloon and the truck are both moving with the wind in the same manner as far as velocity vectors are concern.

0 Replies

@DrewDad,

DrewDad wrote:

Bill,

Just gear down the wheels and you get steady-state movement upwind. You might not move very fast, but you will definitely move continually upwind.

This is almost trivial to describe. Have a windmill generate electrical power and have the electricity power the wheels. No flywheel needed.

Haha, you're right! I was running the linkage in reverse, in my mind, of how it works on the car.

Cycloptichorn

1 Reply

@DrewDad,

Quote:

Just gear down the wheels and you get steady-state movement upwind. You might not move very fast, but you will definitely move continually upwind.

Sorry gearing will not do that feat let see if I can find an analogy off hand.

Replaced the wind force with the force of gravity on a hanging weight and your gearing with a pulley system that will act in the same manner.

The pulley system will redirect the force and and gear it down in the same manner you are claiming for the wind car.

Now can you see the weight moving slowly upward or not?

1 Reply

@Cycloptichorn,

Sorry once more neither will not work.

Sound good until you think about it however.

Gearing will not add energy it just change the relationship between force and distance.

1 Reply

@BillRM,

BillRM wrote:

Sorry once more neither will not work.

Sound good until you think about it however.

How do you reconcile this with video evidence showing that the car does in fact work? Do you posit a secret engine somewhere on the car? Laughing

Cycloptichorn

1 Reply

@Cycloptichorn,

Quote:

How do you reconcile this with video evidence showing that the car does in fact work? Do you posit a secret engine somewhere on the car?

Sorry but a weight of a video that was created and edit by the Blackbird group is zero.

Lot of amazing videos on Youtube.

0 Replies

@BillRM,

Your problem, here, is that gravity Not Equal

wind, so that's a really bad analogy.

If you can't visualize how to make a windmill car go steadily upwind, then you pretty much fail at physics....

0 Replies

@BillRM,

Quote:

The wind blowing over the ground does indeed subject non-moving objects attached to the ground to the full forces/pressures of the wind and if you place a windmill or such a device attached to the ground you can indeed extract energy.

Out of the mouths of babes.

Quote:

Now place that same windmill on a flat bed truck moving [...]

1) it's not a windmill but that's not the primary mistake in your analogy,

2) the DDWFTTW prop is not on a flat bed truck disconnected from the ground.

Missing that point is the remaining flaw in your thinking and is why almost everything you have written to this point has been irrelevant, so read it again. Though not fixed wrt the ground, the prop is attached to the ground through the drive train and therefore can indeed extract energy from the movement of the wheels over the ground. The ground moving under the wheels is analogous to the air moving over the blades of a windmill. The prop is not in any way analogous a windmill providing energy through the drive train to turn the cart wheels to propel the cart so this is not perpetual energy or over unity in any sense. The thermo diagram above demonstrates what is going on:

3) the prop and drive train span two media at different potential energies.

That is an incontrovertibly true statement and the fundamental reason why DDWFTTW works. Whether the prop is moving wrt the ground is not important: what is important is that it is attached to the ground through its drive train.

Every one of your objections are either irrelevant wrt to statement (3) above or just plain wrong; none of your objections refute that statement, nor do they refute statements (1) or (2).

The rest of the details of the DDWFTTW cart are clever gearing (or leverage, if you prefer).

1 Reply

@DrewDad,

DrewDad wrote:

Wind-powered car goes down wind faster than the wind

Quote:
(PhysOrg.com) -- A wind-powered car has been clocked in the US traveling down wind faster than the wind. In a recent run at New Jerusalem in Tracy, California, the car reached a top speed of more than 2.85 times faster than the wind blowing at the time (13.5 mph) powered by the wind itself. The run should now settle the DWFTTW (down wind faster than the wind) debate that has been raging for some time on the Internet about whether or not such a feat was possible.

...

Cavallaro explained the car is able to move faster than the wind because the propeller is not turned by the wind. The wind pushes the vehicle forward, and once moving the wheels turn the propeller. The propeller spins in the opposite direction to that expected, pushing the wind backwards, which in turn pushes the car forwards, turning the wheels, and thus turning the propeller faster still

Wow. That's pretty ingenious. I'll take a crack at explaining how:

Think of a sail car with a single ordinary sail. For example's sake; let's say the sail is operating at 50% efficiency in propelling the car. But what if the sail was 10 times larger? Obviously, this wouldn't work because a significant percentage of the ambient air speed is all you could hope to achieve. Enter this ingenius configuration. Since a propeller is able to apply force against the ambiant wind; the propeller itself acts as a VERY large sail.

To help get your head around it; consider how air acts in a venturi. Similarly, this design is able to capture force from a greater area, and squeeze it into a smaller one for greater speed.

1 Reply

@sirclicksalot,

Sorry there is no energy to be have from the wheels other then Kinetic energy of the car and taping that to spin your props will slow down the wind car not speed it up!!!!!!!!!!!

Sorry you need a motor in a very bad way Very Happy

1 Reply

@BillRM,

Quote:

Quote:

Do you agree a cart with a turbine on it driving the wheels could move directly upwind?

Well you could for example set the brakes and then spin up a flywheel and after releasing the brake move forward on the flywheel energy for a time.

So you could move directly upwind by stages if you wish to but I do not see steady state movements.[corrected spelling]

Wow. Would you mind describing or diagramming the force and energy balances that bring you to this conclusion?

1 Reply

@sirclicksalot,

Quote:

Wow. Would you mind describing or diagramming the force and energy balances that bring you to this conclusion?

I will let you go first and after you get done with that task you can show how a weight hanging from a pulley can go upward.

2 Replies

@BillRM,

Quote:

Sorry there is no energy to be have from the wheels other then Kinetic energy of the car

There is energy available from the differential velocity between the ground and the wind to any device connected to both. Sorry I can't say it any more plainly than I said it above, but you continue to ignore and/or violate fundamental physics and so you are wrong.

0 Replies

Here's one for you Bill

If you have 2 vehicles.
Both have the same size sail.
One weighs twice as much as the other.

Can you agree that given enough time they will both achieve wind speed?

1 Reply

@parados,

Two vehicles of what kind?

And are we ignoring friction with the ground?

0 Replies

@BillRM,

Strawman.

Nobody here has made a claim that a weight attached to a pulley would go upward....

0 Replies

@BillRM,

Quote:

Quote:
Wow. Would you mind describing or diagramming the force and energy balances that bring you to this conclusion?

I will let you go first and after you get done with that task you can show how a weight hanging from a pulley can go upward.

Vt = true wind velocity wrt ground, downwind
Vc = cart velocity wrt ground, upwind

Force balance:

Fp = force of wind on prop, pushing cart backward
Fq = drag and friction forces (small by design), pushing cart backward
Fg = force of wheels on ground, pushing cart forward (Newton 3)

At steady state, forces forward = forces backward, no acceleration:

Fg = Fp + Fq

Power balance:

Pp = power obtained from prop = Fp * (Vt+Vc), input
Pq = power losses (again small by design), output
Pg = power applied to ground, output = Fg * Vc

At steady state, power inputs = power outputs, no accumulation:

Pp = Pg + Pq

also

Fp * (Vt+Vc) = Fg * Vc + Pq

rearranging

Fp * Vt = (Fg - Fp) * Vc + Pq

substituting Fq for (Fg - Fp)

Fp * Vt = Fq * Vc + Pq

and finally solving for the speed ratio:

Vc / Vt = (Fp - Pq/Vc) / Fq

so both balances can be satisfied simultaneously with Vc/Vt positive or even over one if losses (Pq and Fq) are kept low enough; keeping the losses low is a design hurdle, not a fundamental theoretical hurdle. Getting Fg up to the necessary level is only a matter of gearing (design) because input power from Fp is available at (Vt+Vc) while the output drive power to the wheels is applied at the larger Fg but at only Vc. Note also that as the design Vc/Vt or as Vt goes up so do Fq and Pq which makes it harder satisfy that last equation, so this is not an over-unity system.

Your weight and pully thought experiment is another irrelevant analogy.

2 Replies

I don't understand how this car works.

Related Topics

Quick Links

My Account

able2know